The exodus began in the UK last week when British government departments, the Royal Navy and Royal Air Force withdrew their digital advertising from the Google-owned company after they appeared next to videos promoting anti-Semitism and homophobia.
The move was followed by a number of large British corporations including retailer Marks and Spencer Group and supermarket chain Sainsbury.
The head of Google's UK unit Ronan Harris penned a blog post in response to the advertiser backlash last week, saying the company could do a better job.
Mr Harris said that Google removed nearly 2 billion offensive ads last year and also blacklisted 100,000 publishers from the company's ad sense program, but admitted that the company "don't always get it right".
He said that Google had heard the advertisers' message and would work to prevent customers' ads appearing next to videos that promote terrorism, white supremacy and other forms of extremism.